A theoretical study of the isomerization and dissociation processes of the HO–CO+ ion: interstate crossing in the formation of H–CO++O11Dedicated to Professor Mike Bowers in recognition of his impressive contributions to the field of mass spectrometry and ion processes.

Low energy HO–CO+ ions [ΔHf(298) = 142 ± 2 kcal/mol] uniquely dissociate to H–CO+ + O. From ab initio molecular orbital calculations a mechanism is proposed which involves a 1,2-hydrogen shift of HO–CO+ (1A′) to H–CO2+ (1A′) followed by an interstate crossing leading to a transient triplet 3A″ state which then dissociates into H–CO+ (1Σ) + O (3P). This mechanism provides a satisfactory explanation of the observed kinetic energy release and …